Midterm postoperative outcomes of different types of surgical reconstruction of sinus venosus atrial septal defects with anomalous pulmonary venous connection: The Results of Prospective Cohort Study

Abstract Background and Aims Sinus venosus atrial septal defects (SVASDs) constitute a substantial part of atrial septal defects and are usually characterized by anomalous pulmonary venous connection (APVC), causing complications like sinus node dysfunction and arrhythmias. Several surgical approaches are used for treating SVASDs in pediatric patients, including single‐ and two‐patch techniques. The study aimed to prospectively evaluate and compare the safety and efficacy of these two methods with different follow‐up periods. Methods Ten patients aged 1–8 years with SVASDs and partial APVC were enrolled in the study at Bhanubhai and Madhuben Patel Cardiac Centre, Karamsad, India, between December 2018 and October 2021. The single‐patch (sandwich‐patch) technique was used in two patients, whereas the two‐patch (dual‐patch) technique with autologous pericardium was used in seven. Safety was assessed as the absence of complications in the follow‐up periods of 6 months, 1, and 2 years, whereas efficacy was estimated by the preserved sinus rhythm and the development of arrhythmias. Electrocardiographic and echocardiographic methods were used to evaluate both parameters. Results No deaths, reoperations, pulmonary vein, and superior vena cava (SVC) stenosis or phrenic nerve palsy were observed among the 10 patients in the three follow‐up periods. Sinus rhythm was arrested in two of the seven patients who underwent two‐patch repair, whereas no rhythm disturbances occurred in those who underwent single‐patch repair. Conclusion Both techniques used in SVASD repair with autologous pericardium proved to cause the smaller rate of complications in midterm postsurgical phase. However, there is a potentially great risk of the development of sinus node malfunction after the application of the two‐patch technique. Therefore, methods avoiding sinus node interference are preferred in patients with partial APVC involving SVC.

However, there is a potentially great risk of the development of sinus node malfunction after the application of the two-patch technique. Therefore, methods avoiding sinus node interference are preferred in patients with partial APVC involving SVC.

| INTRODUCTION
Sinus venosus atrial septal defects (SVASDs) are relatively rare congenital heart defects belonging to one of the major groups of atrial septal defects (ASDs). They were first described in 1858 and compose around 4%-11% of ASD cases. 1,2 SVASD can be described as the deficiency of connective tissue at the posterior aspect of the atrial septum that is clinically manifested as atrial communication with the superior or inferior vena cava (IVC). In the former case, they are usually accompanied by anomalous pulmonary venous connections (APVC) from the right superior pulmonary vein (RSPV) to the SVC. 3,4 Left-to-right shunt is produced because the left atrial pressure exceeds that of the right, and longterm effects are associated with the overload of the right heart, such as pulmonary hypertension.
The major surgical principle of treatment is providing the bypass for the venous flow to the left atrium (LA) by redirecting APVC through the junction of the left and right atriums (RAs).
Surgical interventions possess certain risks due to the complexity of the performed procedures compared to surgical reconstruction of secundum ASD. The major complications in the postoperative period include the risk of reduced blood flow in the SVC or pulmonary veins, residual shunting, and sinus node malfunction. 4 The two common surgical methods used for the treatment of malformation are single-and two-patch techniques (Figures 1 and 2).
Due to the abnormal direct connection of pulmonary veins with SVC, the latter is the more common method of choice. In this technique, one patch is used to close the ASD and another to close the right atriotomy at the cavoatrial junction to decrease the risk of stenosis. 5 Although most reported studies are in favor of the better efficacy of the former, there is no unified consensus on the application of these methods in particular clinical cases. Most existing works focus on the long-term prognosis of their application, whereas the complications in the earlier postoperative time can indicate the safety of the technique. Therefore, this study aimed to assess the rate of complications and sinus dysfunction in midterm follow-up periods as the determinant factors for choice in clinical situations.
In all patients, preoperative electrocardiography (ECG) was also performed.

| Dynamic cardiac computed tomography (CT)
Dynamic cardiac CT was performed preoperatively in our series for two patients. In patient P4, intracranial arteriovenous malformations were strongly suspected of leading to SVC dilatation. Dynamic In patient P10, left-sided partial pulmonary venous connection to the innominate vein was suspected, and cardiac CT and pulmonary angiography were performed to confirm this (Figures 13 and 14).  We achieved cardioplegic arrest with Del Nido cardioplegia and topical slush saline. We did not routinely use a left ventricular vent.
All patches were made from the fresh autologous pericardium. In two F I G U R E 3 Gender distribution of patients in this study  None of the patients in our series required the Warden procedure (Figures 22-24).
In patient P10, we rerouted the PAPVC by creating an anastomosis between the left atrial appendage and the vertical vein with flush ligation of the vertical vein and the innominate vein, leaving the hemiazygos vein in the systemic pathway. We used a glutaraldehyde-treated pericardial patch to close the ASD and performed pulmonary valvotomy.
The intraoperative characteristics are represented in Table 1, including cardiopulmonary bypass and aortic cross-clamping times.

| Postsurgical phase
Complete follow-up was obtained for all 10 patients at 6-month, annual, and bi-annual intervals.

| Echocardiographic findings
The 2D echocardiograms were evaluated at the time of discharge and at follow-ups. Changes appearing at the SVC-RA junction, such as flow acceleration, and changes in the peak gradient were assessed (

| PV and SVC stenosis assessment
The grading for the stenosis of SVC and RSPV was determined as trivial, mild, moderate, or severe. This parameter was assessed in the three follow-up periods.

| RESULTS
In this series performed between 2018 and 2021, no mortality was The association between technique (single-vs. two-patch) and rhythm was not significant (p > 0.999; Figure 25).
Two patients, P4 and P7, who underwent two-patch repair exhibited junctional rhythm on early ECG (Figure 26).
This junctional rhythm returned to sinus rhythm on late ECG in the hospital. The remaining eight patients displayed normal sinus rhythm on early ECG. The 2D echocardiographic findings of patient P2 on discharge revealed turbulence at the SVC-RA junction with peak and mean gradients of 18 mmHg each. Subsequent echocardiographic findings of the same patient at the 6-month, annual, and biannual follow-ups revealed diminishing gradients with peak and mean gradients of 10/6 mmHg. each. Patient P2 has been monitored for the last 3 years and continues to be free of SVC occlusion symptoms.
All seven patients who underwent two-patch repair continue to be monitored at our cardiac center. In the two patients who underwent single-patch repair, turbulence was noted in the SVC-RA junction pathway: patient P1 exhibited peak and mean pressures of 4 and 2 mmHg, respectively, and P2 exhibited a peak and mean pressures of 18 mmHg each. No rhythm abnormalities occurred after single-patch repair. 6

| DISCUSSION
Since the earliest reports of the anomaly, the repair of SVASD with PAPVC involving the SVC was a serious issue imposing potentially high risk of complications. 8,9 To redirect pulmonary venous return, there are numerous surgical modifications. As reported in many surgical series, the major complications at the early stage have been mostly resolved, but the stenosis of SVC and pulmonary veins, along with sinus node dysfunction remains the same. In our study, PAPVC involving SVC at a low level, RA, or both was treated by septal transposition 10 or by providing the bypass for the anomalous pulmonary venous flow to the LA through the ASD and with a patch applied from within the RA. 11 We did not encounter cases in which PAPVC was involved with the SVC at a high level (≥1 cm above the cavoatrial junction) with or without the associated ASD.
In the literature review, we found a very low incidence of stenosis of the SVC or pulmonary veins with the use of the two-patch technique. According to previous studies, there is a significant incidence of sinus node malfunction after two-patch repair, which involves an incision crossing the SVC-RA intercommunication anteriorly or laterally, thereby making potential damage for the sinus node. In a review by Delon et al., 11  whom only 1 had continuing sinus node dysfunction. 12,13 In contrast, only two of them had sinus node dysfunction in the early period, while the normal sinus rhythm was achieved by 5 days and 6 months after surgery.
In the pediatric cases of SVASD with PAPVC involving high levels of the SVC, the Warden procedure encourages the flow of blood in the SVC and pulmonary veins, possibly diminishing the risk of sinus node dysfunction that is associated with two-patch repair; therefore, this procedure should be regarded as an option.
Even in patients aged >40 years, this procedure has lower risks, although it is characterized by multiple challenges. Although early repair is recommended, the survival rates say in favor for the procedure. 6 A study by Shahriari et al. 14